Despite Königsmarck’s detaching himself from the Franco-Hessian armies, the Bavarians were still considerably outnumbered. Nonetheless, they determined to give battle to the French at Alerheim, near Nördlingen.

There, on 3 August, 1645, the Bavarians were driven from the field in a bloody battle that cost the life of the Bavarian general Mercy. The conflict left the French too weakened to follow up on their advantage, although they did occupy Nördlingen.